Datasheet

LT1950
2
1950fa
ORDER PART
NUMBER
GN PART MARKING
T
JMAX
= 125°C, θ
JA
= 110°C/W,
θ
JC
(PIN 8) = 30°C/W
1950E
1950I
LT1950EGN
LT1950IGN
ABSOLUTE AXI U RATI GS
W
WW
U
PACKAGE/ORDER I FOR ATIO
UUW
(Note 1)
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. COMP = open, FB = 1.4V, R
OSC
= 249k, SYNC = 0V, SLOPE = open, V
REF
= 0.1µF, SHDN = V
IN
, BLANK = 0V, I
SENSE
= 0V, V
IN2
= 15V, GATE = 1nF, BOOST = open, V
IN
= 15V, V
SEC
= 0V, unless otherwise
specified.
Consult LTC Marketing for parts specified with wider operating temperature ranges.
TOP VIEW
GN PACKAGE
16-LEAD NARROW PLASTIC SSOP
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
COMP
FB
R
OSC
SYNC
SLOPE
V
REF
SHDN
GND
V
SEC
V
IN
BOOST
PGND
GATE
V
IN2
I
SENSE
BLANK
PARAMETER CONDITIONS MIN TYP MAX UNITS
PWM Controller
Operating Input Voltage I
VREF
= 0µA ● 3.0 25 V
Minimum Start-Up Voltage I
VREF
= 0µA ● 2.6 3.0 V
V
IN
Quiescent Current I
VREF
= 0µA, FB = 1V, I
SENSE
= 0.2V 2.3 3.0 mA
V
IN
Shutdown Current SHDN = 0V 5 20 µA
Shutdown Threshold 3V < V
IN
< 25V ● 1.261 1.32 1.379 V
Shutdown Pin Current SHDN = 70mV Above Threshold –7 –10 –13 µA
Shutdown Pin Current Hysteresis SHDN = 100mV Below Threshold 4 7 10 µA
V
IN2
Quiescent Current I(V
REF
) = 0µA, FB = 1V, I
SENSE
= 0.2V 1.7 2.5 mA
V
IN2
Shutdown Current SHDN = 0V, V
IN2
= 2.7V (Boost Diode from V
IN
= 3V) 500 700 µA
V
REF
(External Output)
Output Voltage I
VREF
= 0µA ● 2.425 2.500 2.575 V
Line Regulation I
VREF
= 0µA, 3V < V
IN
< 25V 1 5 mV
Load Regulation 0µA < I
VREF
< 2.5mA 1 5 mV
Oscillator
Frequency: f
OSC
R
OSC
= 249k, FB = 1V ● 170 200 230 kHz
Minimum Programmable f
OSC
R
OSC
= 499k 85 100 115 kHz
Maximum Programmable f
OSC
R
OSC
= 90.9k 440 500 560 kHz
SYNC Input Resistance 20 kΩ
SYNC Switching Threshold 1.5 2.2 V
SYNC Frequency/f
OSC
(R
OSC
= 249k, f
OSC
=200kHz), FB = 1V (Note 7) 1.25 1.5
f
OSC
Line Reg 3V < V
IN
< 25V 0.05 0.15 %/V
9.5V < V
IN2
< 25V 0.05 0.25 %/V
V
ROSC
1V
BOOST ....................................................... –0.3V to 35V
V
IN
, V
IN2
, SHDN ......................................... –0.3V to 25V
FB, SYNC, V
SEC
........................................... –0.3V to 6V
COMP, BLANK .......................................... –0.3V to 3.5V
SLOPE ...................................................... –0.3V to 2.5V
I
SENSE
......................................................... –0.3V to 1V
R
OSC
.................................................................... –50µA
V
REF
.................................................................... –10mA
Operating Junction Temperature Range
LT1950EGN/LT1950IGN (Notes 2, 5) ... – 40°C to 125°C
Storage Temperature Range ..................–65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C